This invention relates to welding machines of the type used in manufacturing plants for production of welded parts. More particularly, it relates to electric welding machines such as resistance welders and metal-inert gas (MIG) welders.
It has been a common practice in the welding machine industry to build welding machines with custom tooling as an integral part of the welding machine. In this practice, especially in connection with resistance and MIG welding machines, each machine is dedicated to the manufacture of a particular part and is not useable for manufacture of other parts. The working area of such a dedicated machine includes an attached assembly of fixtures and tools specifically made, located and adjusted to produce the parts to which the machine is dedicated. The entire machine, from heavy frame to built-in precision fixtures is treated as capital equipment on the financial books of the purchaser. When the parts produced by the dedicated machine are no longer needed, the entire machine is generally scrapped.
There has been a longstanding need in the industry to overcome the disadvantages which accompany the practice of using dedicated welding machines such as the economic loss from scrapping the entire machine when the tools and fixtures are no longer usable because of wear and tear or because of termination of production of the part to which the machine is dedicated. A general objective of this invention is to provide a solution to the problem of economic loss associated with dedicated machines by extending the useful life of those parts of the machine which are not dedicated to a particular product. That part of a given machine, except for the dedicated fixtures and tooling, is herein sometimes referred to as the xe2x80x9cbase operating machinexe2x80x9d whereas the dedicated fixtures and tooling are herein referred to as a xe2x80x9ctooling modulexe2x80x9d.
In the prior art, the Henry U.S. Pat. Nos. 4,473,734 and 4,594,494 granted Sep. 25, 1984 and Jun. 10, 1986, respectively, describe a base machine which is adapted to receive interchangeable welding modules. These patents describe an arrangement wherein the base machine is provided with a welding head and a foot treadle actuating device for the upper electrode. Welding current is supplied in the base machine through conductors connected to a conductive base member and to the welding head. The welding electrodes receive welding current through a conductive plate on the module and a movable contact in the welding head.
In Muller et al. U.S. Pat. No. 5,093,977 granted Mar. 10, 1992, a welding machine is described which is adapted for processing differently shaped workpieces with a controlled tool changing capability for quick change of the set of tools. In this system, a central work station is provided with a workpiece holder. More than one tool frame is mounted on the machine and each tool frame may be moved from one station to another. When the processing of the workpiece has been completed by a selected tool frame at the central work station, the processed part may be conveyed out of the station. If other processing operations are to be carried out on the same workpiece or if the processing of a workpiece of a different shape is desired, another tool frame is moved into the central work section after the previous tool frame has been moved out. The processing of the workpiece is accomplished by the substituted tool frame.
It is a general object of this invention to provide a modular welding machine which overcomes certain disadvantages of the prior art.
In accordance with this invention, a modular welding machine comprises a base operating machine which coacts with a removable tooling module which is operatively coupled with the base operating machine to receive actuator fluid pressure supply and electrical signals through quick disconnect connectors of the push/pull type. Further, according to the invention, when the tooling module moved is into its installed position the weld current contactor members on tool module are engaged with the contactor members on the base operating machine.
Further, according to the invention, a machine connector plate supports a plurality of connector members and a tooling module connector plate supports a plurality of complementary connector members for mating engagement with the connector members on the machine connector plate when the tooling module is situated in the installed position. Preferably, mating engagement is carried out by actuation of the machine connector plate to engage the module connector plate. Preferably, the connector plates carry first and second locating members respectively for aligning said complementary connector members for movement into operative engagement.
Further, in accordance with the invention, the tooling module and the base operating machine are provided with coacting guide means for facilitating movement of the tooling module into or out of the installed position of the module. Preferably, a module transfer cart is provided with alignment means coacting with said base operating machine with guide means on the transfer cart for moving the tooling module onto the guide means of the base operating machine.
Further, in accordance with this invention, interlock means are provided to inhibit operation of the welding machine unless the tooling module is properly installed in the base operating machine.
Further, in accordance with the invention, a parts transfer device may be provided with complementary parts mounted respectively on the machine connector plate and the module connector plate for feeding small parts from the base operating machine to a workpiece positioned on the module.
A complete understanding of this invention may be obtained from the detailed description that follows taken with the accompanying drawings.